Fuse



y 1943- H. J. NIICHOLS 93 FUSE Filed Nov. 14, 1959 Im mn Patented May 181948 UNITED STATES ATENT FEECE 9 Claims.

This invention relates to base detonating fuses,

especially adapted for use with anti-tank projectiles and other smallcaliber high-explosive projectiles intended for use against armored orprotected targets.

The invention will accordingly be hereinafter described with relation tosuch application but it is to be understood that without materialmodification many features are equally applicable to larger caliberprojectile fuses.

Detonating fuses for small high explosive projectiles present particulardifiiculties because of their small size, the great accelerating androtary forces to which the parts are subjected in firing and in flight,and the heavy forces encountered at impact. Because of the desire toobtain maximum penetration of armor, a nose fuse, which wouldnecessitate weakening the front end of the projectile is generallyconsidered undesirable and a base fuse is preferred. Because of theextreme force of set-back, on firing some projectiles the detonator maybe fired by concussion. Also the detonator may be subject to accidentalexplosion by fire while the fuse is in storage, transport, or service.These hazards make it highly. desirable that the fuse be detonator-safe,by which term is meant that the detonator be held in safe position inthe fuse until the projectile has cleared the muzzle. A furtherdesirable feature is that the fuse be not completely armed until theprojectile has travelled some distance beyond the muzzle of the gun.This is termed a "muzzlesafe feature. In order to insure certain armingand sensitivity, it is highly desirable that the percussion device bevirtually dynamically balanced with respect to the axis of rotation ofthe projectile in flight, which is also the axis of the fuse.

Finally, from the practical standpoint, fuses of this class should besimple in construction, easily loaded and assembled, and adapted to lowcost manufacture in large quantity.

It is therefore one of the principal objects of this invention to meetin a highly eficient, reliable, and practical manner the general andspecial requirements above stated.

Another object is to provide simple and rugged arming means whichutilize forces generated .by the firing process, but- Which are notaffected adversely thereby, nor by the forces and shocks incident tohandling. 7

Another object is to provide a high degree of safety against prematureexplosion in handling the fuse, or on firing the loaded and fusedprojectile.

- hazards.

2 Another object is to provide means for delaying the arming of thedetonator until after the projectile is in flight, or muzzle-safe"feature.

Another object is to provide a novel and effective bore-safe anddetonator-safe construction as a precaution against concussion or fireAnother object is to provide simple and practical means for cushioningthe shock on the detonator on firing.

Another object is to provide simple arming means for the detonator whichafter rotating the detonator is inherently incapable of being thrownfrom armed position by forces produced by impact with the target.

Other objects will in part be obvious from the annexed drawings and inpart hereinafter indicated in connection therewith by the followinganalysis of the invention.

This invention accordingly consists in thefeatures of construction,combination of parts, and in the unique relation and coordination of themembers and in the relative proportioning and disposition thereof, allas more completely outlined herein.

To enable others skilled in the art fully to comprehend the underlyingfeatures of this invention, that they may embody the same by thenumerous modifications in structure and relation contemplated by theinvention, drawings depicting a preferred embodiment of the inventionform a part of this disclosure, and in such drawings like characters ofreference denote corresponding parts throughout the several views, inwhich- Fig. 1 shows greatly enlarged, in longitudinal section a basepercussion detonating fuse of small size according to the invention, themechanism ,being shown in unarmed or safe condition.

.cross section in armed position.

Fig. 3 is a top or inner end view of the fuse.

Fig. 4 is a bottom or base view of the fuse.

Referring now to these drawings and especially to Fig. 1, the mainmemberof the fuse is the body I!) of rugged proportions with flange H andexternal screw threads l2 near the base end l3 for assembly to theprojectile (not shown). The body Ill is bored out from the point end i lto provide an internal bore I5 in which the mecha- ,nism is assembled.Starting at the base l3, a

small axial core or cavity i8 is threadedto receive the lower portion ofan anti-creep spring ll. A middle bore or cavity 58 is adapted to housea percussion plunger 28, to be described in detail later. The nosecavity 2i is adapted to receive a rotor sleeve 22, mounting a rotarydetonator holder or centrifugal rotor 23, and also a booster cup 24,containing a booster charge of compressed -.tetr y1 or the like. Thepoint end is. of the fuseiis closed by a sealing'di'sc 25, over which alip 27 of the fuse body is spun, or otherwise closed or constructed toform a tight seal. The parts 22 and 2 may be die-cast integrally, ifdesired.

The percussion plunger 28 comprises asupport or pedestal 23 having aninternally threaded cavity 29 adapted to receive the upper :portion ofanti-creep spring ll, the threads being .bored out for a short distanceat the mouth of cavity '29 to enable the middle coils of spring ll tostretch without interference "with the screw threads. 'The purpose ofthis spring ll is to prevent the percussion :plunger 29 from beingthrown forward after firing when the projectile strikes the atmosphere,and during flight.

The percussion plunger includes element 30 of hollow cylindrical form,which is substantially closedat the top 3 I, and hasan internal-cavity32 fitting easily over the pedestal '28. 'Mou nted'in the axis of theelement 30 is a firing pi-n33 comprising a firing point 3' 2, a collar-35 and a=s lightly tapered punch'36 at the opposite end. Collar 35 issecurely "set in a recess 16: in the element '30 by riveting the edge ofthe recess 'over the collar. Punch 36 rests on top of pedesta-1'2 3,which latter is of such thicknes that when the fuse is fired, theset-bac'k force on element "3 9 and firing pin 33 w illcause the punch3-6 to pierce the top o'f the pedestal 28 and to remain securely wedgedtherein due to the taper on the punch see Fig. 2).

The 'rotor sleeve 22 is of hollow cylindrical form with a rectangular-hole adapted to receive the rotor 23, the latter being of shortcylindrical form and lying edgewise in rotor sleeve '22. The

rotor has a diametrical round hole adapted to L receive a cylindricaldetonator :capsule :40. The detonator capsule is preferably a thin drawncopper shell, in which a highly compressed detonating'c'h-arge "isloaded. The assembly of the detonator isnompleted by covering thedetonati-ng charge, loaded not quite to the top, :b-y a thindisc 4cemented in place by a water iprodf -icement. When the detonator capsuleare :is loaded "into the rotor, it is coated with a strong adherentcement to hold the capsule securely in place in the rotor .23. The rotor:is :providedwith rarsmall tapered hole 38 (Fig. 2') located at an angle'cof approx mately :to the axis :of the detormtor Ml, this .h'olezb'eingadapted tozreceive the point $4 of the illing pit-1 33 when the rotor is:in safe position asshown in Fig. 1.

The rotor '23 is :of centric-symmetric form, being of the typefilSClDSBd in my application Serial No. 1303294, filed November "7,.1939, so that while is virtually statically ibalan'cedasiit liesfin bheit is strongly dynamically unbalanced with :respectto rotationabout theaxis of the fuse, which is likewise substantially-the axis of rotationof the projectilewh-ile in flight. V

lRreferring td-Fig. 2d, on, each-end of the rotor 23a central. channel'43 may be cut at slight inclination'to the axis of the detonator Ml.This leaves two symmetrical lands M on each end of the rotor,oisegmental shape, which lands produce the dynamic unbalance. Thedynamically unbalanced areas are indicated by the portions between thedotted lines and periphery of the holder as shown in Fig. 2. There isalso some minor unbalance due to the detonator capsule and the firingpin hole 38, but the rotative effect produced thereby is generally toosmall to be material, and for purposes of understanding the principle ofthe rotor, the lands 44 may be considered to produce the-main andeffective rotative effect. The-slight iinc'lination of these lands tothe axis of the detonator hole, previously men- .tioned suflices tocompensate for minor unbal- 'ance and friction, so that after firing theaxis of the detonator is aligned substantially with the axis .of thefuse. It has been found that the channel separating the lands can beparallel to *theraxisiof :the detonator in most cases.

Referring again to Fig. 1, between a shoulder 2! in the 'bore l5 of thefuse body H3 and the rotor sleeve 22 is assembleda disc 45, termed thesupport discgofthin elastic:metal arranged to cushion the shock on thedetonator M! on firing, thereby minimizing the possibility of prematuredetonation due to concussion. The disc 55 is provided with a small axialhole 36 .thru which "the point- 34 of :firin'g .pin 33 normally extendsto engage thehole iw 'an-d restrain the rotor in .safe position.

The booster oup 24 is mounted between the rotor block 22and-sealingdiscflfi. It is provided :a small :diameter -axial hole "M,counter bored :at ithe upper end to receive a small metal cup 48,halld'the icord "protector icu'p. The interior of the cup.;is 'ffilleflwith tightly compressed cord :or 'tetryl :or the like for transmittingthe detonation from the detonator .to the "booster chargeflfi. purposeof the cup "48 is to protect'rthe' :cm'dfrom moisture, and :also".fIOIll hot .gasestlikely'ltobe pruduced'in :event of prematureexplosion lot "the detonator 455.

The :fuse :is assembled into the projectile by .spannersrengagmgvrecesses 549 :as shown in Figs. -1 ands. the ioperationiis asfollows: On all ,parts tend :to :move towards the base 1 3'dlreitwset-fba'ck? The element ii] carrying firing pin 3311s "afiected:by :this force, :and :moving backdr ives :therprmchifi t'hruthe :top ofpedestal 2B and causes thersameito-wedgetherein, securely attachingthese :parts as showniin "Fig. 2. The .fir-

3.4 fisthereby drawn :from the hole 38 in :the outer :23 and the rotorwould be free to arm then except'fthatithe set-back" :force presses therotor :tightlyagainst disc 45. The 'rotative force :duetodytramiceunbaflance being minor compared to the "set-back fierce, therotor is prevented fromrotating and remains in the position shown Fig.:1 as done 'zas-the projectile is in the bore of the gun.

it should be :noted here :that not only is 'the motor .Zinnddetonator 40cushioned against the shock :dfwfiring :by .disc -45, but in the eventthe detonator is exploded despite this cushioning or by fire, it-he 8111301; of \the detonator explosion will .be-itoexpandwthe rotor and towedge a plug of .metalgfllqmithe rotor intothe hole :occupiedbytheprotector cup 48 :secunely sealing :same against the entIy oflmt'zgases. The protector :cup'A-B will shield the FtetryI :cord from'mechanical shock to a -degree sulfi'c'ient 1:0 prevent dellagration.The i gases from 'the detonator will expand into voids in the fuse,including "the space over the plunger }3B,;and'wi;llbe cooled andrendered harmless 'by such expansion.

The possibility of the acceleration of theprojectile being reversed inthe bore of the gun due to coppering or other obstruction also requiresconsideration. In such event, the elasticity of the disc 45 will causethe rotor 23 to rebound therefrom and strike the booster cup before itcan respond to rotative forces, and if the percussion plunger 28 ispropelled forward, the firin pin 34 will strike the rotor 23 and retainthe detonator in safe position. Hence it is evident that the inventionprovides adequate safeguards against premature explosion of thedetonator before firing and while the projectile is in the bore of thegun, and the fuse can be properly termed bore-safe.

Referring to Fig. 2 as to position of the percussion plunger 20, and toFig. 1 as to position of the rotor 23, as the projectile leaves themuzzle of the gun, and the force of the propellant becomes spent, theacceleration of the projectile ceases, and deceleration due to airresistance occurs. At this instant, disc 45 will throw the rotorforward, but after rebound, the rotor is free to arm, and at the sametime the rotation of the projectile due to firing is a maximum, hencethe unbalanced forces cause the rotor to turn into the position shown inFig. 2. The fuse is now completely armed and at some safe distancebeyond the muzzle of the gun. The tendency of the percussion plunger 20to pitch forward due to airresistance, termed creep," is countered bythe anti-creep spring II.

On striking a target, the projectile will encounter substantialresistance, and will be checked in flight. This brings into play strongdecelerating forces, and the percussion plunger 20 will be propelledforward, overcoming the anticreep spring I! and stabbing the firing pininto the detonator, exploding same. The wave of detonation therefromwill travel through the tetryl cord 48 and booster charge 25 to theprojectile burster charge, not shown but assumed to be of highexplosive, whereby the projectile is fragmented.

It is to be noted that When the rotor 23 is in armed position shown inFig. 2, the dynamic unbalance no longer exists, but there remains atorque couple holding the rotor in armed position and there is notendency towards, nor possibility of, the rotor being thrown out ofarmed position while the projectile is in flight. Furthermore, on impactwith an obstruction, due to the cylindrical shape of the rotor, inertiaforces cause the rotor to wedge tightly in its mounting structure, andit cannot be thrown out of armed position by any combination of impactforces. This is of importance in connection with oblique impact,particularly against armor plate, under which circumstances strongrandom forces are applied to the fuse, and if the rotor can be thrownout of position, incomplete detonation or a dud may result. The rotor ofthe invention is therefore self-locking in the armed position.

While no particular provision is made to obtain delay in bursting afterimpact, it is known that by incorporating in the detonator capsulespecial retarding compositions, a short delay burst can be obtainedwithout material modification of the fuse.

It will be evident to those skilled in the art that the embodiment ofthe invention, shown and de scribed as a detonating fuse, can be readilyconverted into an ignition fuse by simple modifications, such assubstituting a cap or primer for the detonator, a port or powder pelletfor the tetryl cord, and a charge .of powder for the tetryl booster.Such modifications properly come, and

6 are so intended, within the scope of the invention as claimed.

Without further analysis the foregoing will sofully reveal the gist ofthis invention that others can, by applying current knowledge, readilyadapt it for various applications without omitting certain featuresthat, from the standpoint of the prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of the invention, andtherefore such adaptations should and are intended to be comprehendedwithin the meaning and range of equivalency of the follow ing claims.

I claim:

1. In a base detonating percussion fuse, in combination, a fuse bodyhaving an axial bore,'and detonating means assembled therein including abooster holder with a booster charge sealed therein, a stationaryelement having a. cavity with a centrifugally rotatable detonator holdermounted rotatably therein, a detonator mounted in said holder in safeposition, a percussion element for exploding said detonator including afiring pin positioned rearwardly of and in restraining engagernent withsaid holder, means for enabling said firing pin to move rearwardly toarmed position when said fuse is fired in a gun, and means forrestraining forward movement of said percussion element in flight.

2. In a base detonating percussion fuse, in combination, a fuse bodyhaving an axial bore, and detonating mechanism assembled thereinincluding a booster holder containing a booster charge, astationarymember with a cavity having a centrifugally rotatable cylindricaldetonator rotor mounted rotatably therein with its axis at right anglesto the axis of the fuse, a cylindrical detonator mounted diametricallyin said rotor in safe position, a percussion element mounting a firingpin for exploding said detonator slidably mounted in said borerearwardly of said rotor, means including said firing pin formaintaining said rotor in safe position until said fuse is fired in agun, and means for sealng said mechanism in said body.

3. In a projectile fuse of base detonating percussion type, incombination, a fuse body having an axial bore, sealing means therefor,and an assembly of mechanism sealed therein including symmetrical rotormeans carrying a detonator assembled in safe position, rotor meansselfrotatable responsively to centrifugal force for turning said rotormeans and detonator from safe to armed position when the projectile isin flight, and setback armed percussion means including a firing pinpositioned rearwardly of and in restraining engagement with said rotormeans for exploding said detonator on impact of the projectile with thetarget.

4. In the combination set forth in claim 3, said percussion meansincluding a pair of elements normally maintaining said firing pin inrestraining engagement with said rotor means, said elements telescopingwhen the fuse is fired in'a gun to remove the restraint of said firingpin on said rotor means.

5. In detonating mechanisms for base detonating percussion fuses, incombination, a fuse body having an axial bore, and detonating meansassembled therein including a centrifugally rotatable detonator carriermounting a detonator and located with its center of gravitysubstantially on the axis of said bore, a percussion element positionedrearwardly of said carrier including a firing pin for holding saidcarrier in inoperative position until said fuse is fired in a gun andthereafter for exploding said detonator on imdetonating mechanismassembled therein including a stationary member with an axial cavityhaving a centrifugally rotatable cylindrical detonaitor rotor rotatablyand concentrically mounted therein, a detonator mounted diametrally insaid rotor at the center of gravity thereof, a percussion elementpositioned rearwardly of said rotor including a firing pin for explodingsaid detonator, set-back actuated safety means forming part of saidpercussion element for normally holding said firing pin in restrainingengagement with said rotor, and anti-creep means for restraining saidpercussion element from forward movement when alrmed.

"7. A detonati-ng percussion fuse for a rotative projectile having, incombination, a fuse body adapted for assembly into such a projectilehav- :ing an axial bore and closing means therefor, and an assembly ofexploding mechanism enclosed therein comprising, a centrifugal detonatorrotor carrying a cylindrical detonator mounted therein transversely tothe axis of said bore, a percussion device including a movable firingpin positioned 230 axially and in rotation preventing engagement withsaid rotor, and means for releasing said rotor for centrifugal rotationwhen the projectilebarrying said fuse is discharged from a gun.

8. Abase detonating percussion fuse for a rota- :t-i-ve projectilehaving, in combination a fuse body adapted for assembly into such aprojectile having an axial bore and closing means therefor, and anassembly of detonating mechanism enclosed therein comprising, acentrifugal'detonator rotor of circular main section with a detonatormounted .in a diametricail bore therein and transversely to the axis ofsaid body, stationary means for rotatably mounting said rotor, aninertia percussion plunger including a firing pin for exploding said 4:5

detonator positioned axially in rotation preventing engagement with saidrotor, and an anticreep device arranged to restrain movement 'of saidplunger towards said rotor during flight of said projectile.

9. A base detonating percussion fuse for a rotative projectile having,in combination, a fuse body adapted for assembly into the base of aprojectile and having an axial bore with closing means therefor, andexploding mechanism assembled therein comprising, a holder containing anexplosive booster charge, a detonator for initiating the explosion ofsaid charge normally safely positioned in a rotor, a centrifugallyoperated detonator rotor for turning said detonator from safe to armedposition responsively to the spin of said projectile, an inertiapercussion plunger including an axially movable firing pin normallypositioned to prevent rotation of said rotor to armed position, andanti-creep means for restraining said plunger from movement towards saidrotor during flight of the projectile.

HARRY J. NICHOLS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 431,273 Martin July 1, 1890654,108 Ashton July 17, 1900 766,022 Dawson et el .July26, 19041,311,1ce Watson Ju'ly.2'2, 1919 1,311,673 Baldwin July 29, 19191,534,611 Watson Apr. 14, 1925 1,550,977 Lukens Aug. 25, 1925 1,550,978Lukens Aug. 25, 1925 1,865,802 Towner July 5, 1932 1,774,943 SummerbellAug.26, 1930 2,014,393 Mathsen Sept. 1'7, 1935 2,155,100 Scelzo Apr. 18,1939 FQREIGN PATENTS Number Country Date 257,333 Great Britain Aug. 2'7,1926

